1. Field
Example embodiments relate to a semiconductor light emitting device and methods of manufacturing the same. Other example embodiments relate to an active layer, a nitride-based semiconductor light emitting device having an improved structure for optical output performance, and methods of manufacturing the same.
2. Description of the Related Art
A nitride-based semiconductor device has a relatively high melting point and relatively high heat resistance. Because the temperature dependency of the nitride-based semiconductor device is small, the nitride-based semiconductor device may be used for a light emitting device, e.g., a blue/green light emitting diode and a laser diode, and an electronic device, which is a high-speed switching and increased power device. A Group III-V nitride, e.g., gallium nitride (GaN) and/or indium gallium nitride (InGaN), may be a semiconductor material of the conventional nitride-based semiconductor device, and a light emitting device may be formed of the semiconductor material.
The semiconductor light emitting device may include an active layer that converts a current into light. The dominant material of the active layer of the nitride-based semiconductor light emitting device, which emits light having a blue wavelength or longer, may be InGaN. The band gap energy may be tuned by varying the amount of indium (In) in InGaN, thereby controlling the wavelength band of emitted light. The active layer may include a quantum well layer and a barrier layer formed as a pair to have a single quantum well structure and/or a multi-quantum well structure. The multi-quantum well structure may exhibit efficient light emission even at a relatively low current, and may have increased optical output as compared to the signal quantum well structure.
The InGaN-based active layer may have a stacked structure including the quantum well layer and the barrier layer that are stacked in the form of InGaN/GaN, InGaN/InGaN, InGaN/AlGaN and/or InGaN/InAlGaN. As the indium (In) ratio of the quantum well layer becomes higher, the bandgap may become smaller. Consequently, light having a relatively long wavelength band may be emitted. However, when the difference in the In ratio is larger between the quantum well layer and the barrier layer, the temperature instability and chemical instability may cause interdiffusion of the In elements between the quantum well layer and the barrier layer, thereby lowering the optical output of the active layer. Also, the diffusion of the elements may degrade the thin film properties of the active layer.